only in america could two bicycle mechanics launch an aviation industry and so forth. now, what's important here is that all of these figures share a number of key traits. well, one, they were largely or wholly self-taught. that is, they were not products of formal education. as a result, they had freed themselves from the constraints of conventional wisdom and traditional authority. they preferred practical solutions to theoretical discussion. they were, in essence, engineers not mathematicians. in other words, they were supreme practitioners of what i mean by be useful knowledge. be -- now, attempts in general to explain america's technological prowess, i've found, generally revolve around the notion it is our political and social systems that provided the ideal platform for innovation and for the associated economic growth, prosperity and the pursuit of happiness. so in this view it was the new republic shaped by the founding fathers that set the stage for an explosion of innovation during the 19th and 20th centuries. an explosion that we can all agree continues to